Recurable crosslinked cellulose fabrics from methylol reagents and polycarboxylic acids and method of making

ABSTRACT

Cellulosic fabrics are treated with formulations containing methylol crosslinking reagents and polycarboxylic acids having three or more acidic groups per molecule. The treated fabrics are cured in a flat configuration and washed. The fabric is subsequently heated in a folded configuration whereby the folded or creased configuration is permanently imparted to the fabric. A metal salt activating catalyst included in the formulation of the textile treating solution decreases the time required to form sharp, permanent creases in the cured fabrics.

United States Patent 191 Franklin et al.

[ Dec. 17, 1974 RECURABLE CROSSLINKED CELLULOSE FABRICS FROM METHYLOLREAGENTS AND POLYCARBOXYLIC ACIDS AND METHOD OF MAKING [75] Inventors:William E. Franklin; Stanley P.

Rowland, both of New Orleans, La.

[73] Assignee: The United States of America as represented by theSecretary of Agriculture, Washington, DC.

[22] Filed: Oct. 16, 1972 [21] Appl. No.: 298,167

Related U.S. Application Data [63] Continuation-impart of Ser. No.248,200, April 27,

I972, Pat. N0. 3,776,692.

[52] U.S. Cl. 8/116 R, 8/182, 8/183,

3/185, 8/186 [51] Int. Cl D06m l/00 [58] Field of Search 8/l16 R, 181,185, 195,

[5 6] References Cited UNITED STATES PATENTS 3,294,779 12/1966 Bullocket al 8/] l6 UX 3,401,006 9/1968 Perrino 8/] l6 3,676,053 7/1972 Miyakeet al 8/1 16 Primary ExaminerStephen J. Lechert, Jr. Attorney, Agent, orFirm-R. Hoffman [57] ABSTRACT formulation of the textile treatingsolution decreases the time required to form sharp, permanent creases inthe cured fabrics 3 Claims, No Drawings RECURABLE CROSSLINKED CELLULOSEFABRICS FROM METHYLOL REAGENTS AND POLYCARBOXYLIC ACIDS AND METHOD OFMAKING A non-exclusive, irrevocable, royalty-free license in theinvention herein described, throughout all the world for all purposes ofthe United States Government, with the power to grant sublicenses forsuch purposes, is hereby granted to the Government of the United Statesof America. This is a continuationin-part of Ser. No. 248,200, filedApr. 27, 1972, now US. Pat. No. 3,776,692.

This invention relates to chemical treatment of cellulosic textiles.Specifically, this invention relates to imparting durable configurationsto cellulosic textile products. More specifically, this inventionrelates to the chemical treatment of cellulosic textiles with mixturescontaining a methylol crosslinking reagent and a polycarboxylic acid toproduce a product consisting of a crosslinked cellulose derivativehaving acidic, catalytic groups covalently bonded to the cellulose. Morespecifically yet, this invention relates to the production of cellulosictextiles having the properties of wrinkle resistance and smooth drying,but which can be given a heat treatment subsequent to thecure in orderto impart a new durable crease or other configuration to the textileproduct. By the process of the instant invention, cellulosic textiles,garments, and other products may be treated to give them the propertiesgenerally known as durable press, except that the textiles, garments, orother products may be given a heat treatment at any time subsequent tothe cure, thereby imparting durable creases, pleats, or other desiredconfigurations to the textile products. This invention constitutes aprocess which is useful in the preparation of improved cellulosicfabrics or improved blended fabrics.

The main object of this invention is to provide treated textiles ortextile products which have smooth drying and wrinkle-resistantproperties, but which can be given a heat treatment at any timesubsequent to the curing step of the finishing operation in order toimpart new, permanent creases, pleats, or other desired configurationsto the fabric.

Another object of this invention is to provide textile treatingcompositions, formulations, and methods which can be used inconventional textile treating processes to produce wrinkle-resistantcellulosic textile products which can be permanently creased or pleatedat any time subsequent to a conventional precure or postcure step by afurther heat treatment.

Another object of this invention is to provide a process whereby sharp,permanent creases may be formed rapidly in wrinkle-resistant cellulosictextiles using conventional equipment and pressing times.

BACKGROUND AND PRIOR ART It is well known to those versed in the art oftextile treatment that wrinkle-resistant and smooth-drying propertiesare imparted to cellulosic or cellulosic blended fabrics by chemicaltreatments which establish crosslinks between the molecules of thecellulosic fibers. The crosslinks bind the fibers, and therefore thefabric, in the configuration present at the time the crosslinks areestablished. The covalent nature of the crosslinks makes it impossibleto change the configuration of the treated fabric without a chemicalreaction which involves breaking crosslinks and reforming them in newpositions to bind the fibers, and therefore the fabric in the newconfiguration. Conventional delayed cure processes are useful forimparting creases or other desired configurations to textile products,but do not solve the problem of unalterability of finished cellulosictextile products.

In examining the prior art for solutions to this problem ofunalterability of crosslinked cellulosic textile products, we findseveral approaches to solutions of this problem. One approach is throughthe use of thermally reversible crosslinks, that is, crosslinks whichbreak and reform in new positions when heated. Examples of suchcrosslinks are those containing partial chemical structure such asDiels-Alder adducts, aryl biscarbamates, and partial esters ofpolycarboxylic acids. Fabrics with crosslinks such as these can be givenheat treatments to impart new, durable configurations, but long periodsof heat at high temperatures are required to impart sharp, durablecreases in these fabrics, and the fabrics do not have the high wrinkleresistance and smooth drying properties required of durable-pressfabrics.

Another approach to alterable, crosslinked cellulosic fabrics is throughinternally catalyzed fabrics, that is, fabrics containing catalyticgroups covalently bonded to the cellulose of the fibers, along withconventional crosslinks. An example of such a fabric is one prepared byfirst reacting a cotton fabric with reagents which bond quaternaryammonium hydroxide groups to the cellulose, then reacting the resultingfabric with divinyl sulfone to introduce crosslinks into the cellulose.Such a fabric has high resilience and can be given new, durableconfigurations by heat treatments, but the manufacture of such a fabricrequires a number of steps and unusual reagents, and therefore is notwidely accepted by textile manufacturers on the basis of its high cost.

On further examination of the prior art, one finds that polycarboxylicacids are used as crosslinking reagents in processes for producingwrinkle-resistant cotton textiles. In these processes, polycarboxylicacids are used as a sole crosslinking agent and produce a modifiedtextile fabric having partial ester crosslinks, that is, part of thecarboxyl groups of the reagents are in the form of ester groups bondingthe reagent and the cellulose molecules, and the remainder of thecarboxyl groups are in the form of free acidic groups bonded to thecellulose matrix.

In searching the prior art it is also found that numerous carboxylicacids are used as catalysts for crosslinking reactions of methylolreagents with cellulose. These carboxylic acids are used, either aloneor in conjunction with other inorganic catalysts, in small, catalyticamounts to promote crosslinking reactions of the methylol reagents, butit is not the practice or intent to carry out the crosslinking reactionsin such a manner that large amounts of the carboxylic acids becomepermanently attached to the cellulose.

It is also found in the prior art that crosslinked cellulosic fabricsmay be given new, durable configurations when a catalyst is applied tothe cured fabric and the fabric is given a heat treatment. In theseprocesses of the prior art, the ability to accept a new, permanentconfiguration is dependent on the added catalyst, which is not bonded tothe fabric but may be washed out of the fabric with water. The reagentsemployed in this type of recuring process are usually strong catalysts,and consequently have deleterious effects on the strength of the fabricand the durable press properties of the treated areas of the fabric.

THE NEW INVENTION We have now discovered that cellulosic textileproducts may be impregnated with aqueous solutions of conventionalmethylol crosslinking reagent and a polycarboxylic acid containing threeor more carboxyl groups per molecule, dried, and cured, and that theresulting textile product which has high wrinkle resistance and smoothdrying properties and which may or may not be washed to remove excessreagents and which may be given a heat treatment to impart new,permanent creases, pleats, or other desired configurations to thetextile product. The essence of this discovery may be stated as follows:Recurabie durable-press fabrics may be produced by reacting cellulosictextile products with combinations of methylol reagents andpolycarboxylic acids. In this statement the terms recurability anddurable press may be defined as follows: Durable press (as applied tocellulosic fabrics) may be defined as having the properties of highwrinkle resistance, good smooth-drying appearance, and excellentretention of creases imparted to the fabric during the cure. Durablepress properties are generally imparted to cellulosic fabrics byreactions which form crosslinks in the cellulose. Recurability may bedefined as the property of crosslinked cellulosic fabrics being able toaccept new, durable configurations when subjected to a heat treatment,by virtue of a chemical reaction which breaks the crosslinks and reformsthem in new positions.

ln the process of this invention, the polycarboxylic acid serves twoessential functions: (a) by virtue of its acidic nature, thepolycarboxylic acid serves as the catalyst for the crosslinking reactionof the methylol reagent with the cellulose of the fibers, and (b) thepolycarboxylic acid reacts with the cellulose to form partial estergroups which have free carboxylic acid groups which are able to catalyzethe breaking and reformation of the crosslinks from the methylolreagent. The structure of the modified cellulose may be depicted asfollows:

Cellulose g I w R- fi10 H X (:JHa O l Cellulose--- containing methylolreagents and polycarboxylic acids. These activating catalysts, which maybe conventional metal salt catalysts normally used for crosslinkingreactions of methylol reagents with fibrous cellulose, have thefunctionof accelerating the recurring reaction and thus reducing thetime required to form sharp, durable creases in the cured fabrics ofthis invention. This acceleration of the recuring action therefore makesit possible to use fully cured durable press fabrics in garmentmanufacturing operations in which the sewed garments are pressed byconventional methods to form sharp creases and flat seams and do notrequire a postcure step to make these configurations permanent.

Since the combination of polycarboxylic acid and an activating catalystis a very active catalyst system, it is of course necessary to adjustthe conditions to the curing step to obtain a full cure (generallydefined as a good durable press appearance rating and a conditionedwrinkle recovery angle of 280 (W+F) or greater) without causingexcessive degradation of the cellulose and consequent loss of strengthin the fabric. Since the activating catalyst does not become covalentlybonded to the fabric during the cure step, it is not completely retainedin the fabric if the fabric is washed after curing, but thepolycarboxylic acid does become bonded to the cellulose during the cureand the washed fabric retains the same degree of rccurability as thefabrics of this invention not containing the activating catalysts.

The novelty of this additional discovery is based on the fact thatcellulosic fabrics treated with a combination of a methylol crosslinkingreagent with a polycarboxylic acid and an activating catalyst are ableto accept sharp, durable creases at any time after they are cured ifthey are pressed under mild conditions of time and temperature. This isin contrast to durable press fabrics cured with conventional catalysts,which are relatively more resistant to recuring, even if the originalcatalyst is allowed to remain in the cured fabric, than the fabrics ofthis invention containing the activating catalysts. It is possible thatthe higher degree of rccurability of these fabrics is a result of thepresence of relatively large amounts of carboxylic acids which would beefficient catalysts for the breaking of the chemical bonds of thecrosslinks as well as for the formation of new crosslinking bonds. Thiscatalysis of the recuring reactions may be a result of the formation ofmethylol carboxylate groups as intermediates in the recuring reactions.These methylol carboxylate groups would be free to move in the cellulosematrix to positions appropriate for the new configuration being formedin the recuring process. Both the formation of the intermediate groupsand the reattachment of the methylol groups to the cellulose hydroxylgroups would be catalyzed by the activating catalysts. Cured fabricscontaining conventional catalysts or even the newer mixed acid cata:lysts would not have sufficient amounts of carboxyi groups to catalyzerecuring reactions by this mechanism.

In the practice of the invention, substantially any cellulosic textilematerial may be used, but our preferred materials are textile materialsmade either entirely of cotton fibers or of cotton fibers blended withother natural or synthetic fibers. The cellulosic textile material isimpregnated with an aqueous solution containing from 8 to 40% of amethylol crosslinking reagent and from 3 to 12% of a polycarboxylicacid. The solution may also contain other useful textile finishingagents, such as wetting agents or polymeric softeners. The preferredconcentrations of the methylol reagents in the treating solutions arefrom 8 to 12%, depending on the weave of the fabric, and the preferredconcentration of the polycarboxylic acid is from 25 to 50% of that ofthe methylol reagent.

' The methylol crosslinking reagent may be any of the conventionalcrosslinking reagents used for finishing cellulosic fabrics. Thepreferred reagent is dimethyloldihydroxyethyleneurea, but other reagentswhich also may be used include methylated methylol melamines, methylatedureaformaldehyde reagents, methylolated carbamates, formaldehyde,methylol urons, dimethylolpropyleneurea, methylol triazones, anddimethylolethyleneurea.

The polycarboxylic acid may be an acidic organic compound having threeor more carboxylic acid groups per molecule and which is soluble inwater to the extent required in a treating solution. The preferredpolycarboxylic acids are cyclopentanetetracarboxylic acid andtetrahydrofurantetracarboxylic acid. Other carboxylic acids which may beused include mellitic acid, nitrilotriacetic acid,(ethylenedinitrilo)tetraacetic acid, pyromellitic acid,tris(carboxyethyl)isocyanurate, naphthalenetetracarboxylic acid, andbenzophenonetetracarboxylic acid.

After the cellulosic textile is impregnated, it may be dried immediatelyor it may be stored in the wet state or subjected to a fixation processbefore it is dried. The methylol reagent may also be fixed to the cottonfabric, the fabric washed, and the polycarboxylic acid applied in asecond impregnation step. The impregnated and dried textile may be curedimmediately or it may be stored or manufactured into garments or otheruseful articles before it is cured. The curing step consists of a hightemperature treatment carried out in an oven or apparatus such as ahot-head press. The curing step may be carried out at any temperaturebetween 130C and 205C, and for times varying between 15 seconds and 12minutes. The preferred curing conditions are eight minutes at 160C, ineither a forced draft oven or a tenter frame. The cured textile may bewashed with water containing a nonionic detergent to remove unreactedreagents, but this washing is not essential. The cured textile, preparedaccording to the preferred conditions, has a conditioned wrinklerecovery angle of 270 to 295 (W+F) if no softener is used in thetreating solution, and 290 to 310 (W+F) if a softener is used. Textilefabrics prepared according to the preferred conditions of this inventionhave strength retentions comparable to conventional durable pressfabrics.

The cured fabric of this invention is subjected to a heat treatmentduring which it is constrained in the new desired configuration. Thetextile may be constrained by folding it in the desired configurationand applying pressure from a hand iron or other heated object. This mayalso be accomplished with a stem or electrically heated hot-head press.Pressure may be applied in order to produce sharp creases. The textilemay be wet or dry when it is constrained and heated, but of course itbecomes dried during the heating. The temperatures of the heat treatmentmay vary between 130C and 205C, and the time of the heat treatment mayvary from 15 seconds to 8 minutes. In the preferred process, the textileis wet, folded at the position of the desired new crease, placed on apreheated surface, and covered with a heated hand iron. The temperaturein the textile is maintained at C and the textile is held at thistemperature for four to five minutes.

If the cured textile has been washed with an alkaline detergent, it maylose its ability to accept durable creases or other configurations whensubjected to a heat treatment. In this case, the recurability of thefabric may be restored by soaking it for a short time in a very dilutesolution of an acid, for example a solution of 5% or less of acetic acidin water. After this acid treatment, the fabric may be creased by theusual heat treatment as described above.

Fabrics prepared and given heat treatments according to the process ofthis invention permanently retain the creases or other configurationsimparted by the heat treatments. Thus, textiles prepared by thepreferred process and given creases according to the preferred heattreatments retain creases rated at 4.0 or better according to the AATCCcrease appearance test after five machine wash and tumble dry cycles.

In addition, if an activating catalyst is to be used in the fabrictreatment, substantially any catalyst normally used for the curing ofcrosslinking reactions of methylol reagents with cellulosic fibers maybe added to the treatment solution also containing the polycarboxylicacid and the methylol reagent. Our preferred activating catalysts aremagnesium chloride hexahydrate and zinc nitrate hexahydrate, but anymetal salt which behaves as a latent acid when heated to curingtemperatures may be used in the practice of this invention. Otherexamples of such activating catalysts include zinc chloride, aluminumchloride, aluminum chlorohydroxide, ammonium chloride, calcium chloride,and magnesium dihyrogen phosphate.

The amount of activating catalyst to be included in the formulation ofthe fabric treating solution is chosen to give the optimum response toboth the curing step and the recuring step. Generally 0.25 to 1.0% ofthe activating catalyst is used in the treating solution, depending onthe nature and construction of the fabric, the other reagents used, thetime and temperature of the cure, and the degree of cure andrecurability desired in the finished fabric. Larger amounts ofactivating catalysts generally cause severe strength loss and smalleramounts of activating catalysts require more strenous curing conditionsand result in lower recurability of the finished fabric. It is generallypreferable to use smaller amounts of the polycarboxylic acid in thetreating solution if an activating catalyst is also used.

Since the combination of the polycarboxylic acid and the activatingcatalyst constitutes a very active catalyst system, it is possible andpreferred to use milder conditions of time and temperature in the curingoperation. Thus, there activated fabrics may be cured with lower inputof thermal energy and/or with shorter dwell time of fabric in the tenterframe. The optimum curing conditions for each combination of fabric,methylol crosslinking agent, polycarboxylic acid, and activatingcatalyst must be determined by experiments appropriate to the equipmentto be used and the properties desired of the finished fabrics. Ingeneral, the addition of 0.5% of an activating catalyst to the treatingsolution allows a decrease of about 30C in the curing temperature and adecrease of about half of the curing time to obtain wrinkle recovery andstrength retention properties similar to those in correspondingtreatments without activating catalysts. The dried fabrics containingthe methylol reagent, the polycarboxylic acid, and the activatingcatalyst may also be cured by storing them at ambient conditions (2030C)for 30-90 days.

The heat treatments used to form permanent creases or otherconfigurations in the cure fabrics containing the activating catalystsare the same as those used for this purpose with the fabrics of thisinvention without the activating catalysts, except that shorter timesand- /or lower temperatures are required to give equivalent creases.Thus, heat treatments of sec. at 135 to 160C are sufficient to producecreases rated at 5 on the AATCC scale (after 5 laundering cycles) in thefabrics containing the activating catalysts.

SUMMARY This invention can be summarized as a new process and cellulosicether derivatives produced by the new process. The cellulosicderivatives being those resulting from reactions involvingpolycarboxylic acids and dior poly functional N-methylol agents.

The process being one for imparting to cellulosic textiles highresilience and smooth-drying qqualities and capability of qualities tothermal formation and reformation at any time after the cure, theprocess comprising these steps:

a. impregnating the cellulosic textile with an aqueous solutioncontaining:

1. a methylol crosslinking agent selected from the group consisting offormaldehyde dimethylolpropyleneurea bis(methoxymethyl)urontris(methoxymethyl)urea dimethyloltriazonedimethyloldihydroxyethyleneurea highly methylated, fully-methylolatedmelamine dimethylolethyleneurea dimethylolmethylcarbamate, andpartially-methylated trimethylolmelamine; and

2. a polycarboxylic aicid having 3 or more carboxylic acid groups to themolecule, said polycarboxylic acid selected from the group consistingof: mellitic acid pyromellitic acid nitriloltracetic acidcyclopentanetetracarboxylic acid (ethylenedinitrilo)tetracetic acidtetrahydrofurantetracarboxylic acid tris(carboxyethyl)isocyanuratenaphthalenetetracarboxylic acid, and benzophenonetetracarboxylic acid;

b. curing the impregnated cellulosic textile for about from 2 to 12.5minutes at temperatures about from 130 to 205C,

c. optionally washing the cured cellulosic textile with a nonionicdetergent and drying the washed cellulosic textile, and

d. optionally subjecting the cellulosic textile to a heat treatmentwhile constrained with or without pressure for about from 0.25 to 8minutes at a temperature of about from 130 to 205C. 0

Note: There are instances where a drying step would be more suitableprior to the curing step of the process.

This invention also includes a modification of the above processcomprising of these steps:

a. impregnating a cellulosic textile with an aqueous solutioncontaining:

l. a methylol crosslinking agent selected from the same group as above,

2. a polycarboxylic acid selected from the same group as above, and

3. an activating catalyst, which is a metal salt which behaves as alatent acid at elevated temperatures, said activating catalyst selectedfrom the group consisting of magnesium chloride zinc nitrate zincchloride aluminum chloride aluminum chlorohydroxide ammonium chloridecalcium chloride, and magnesium dihydrogen phosphate;

b. curing the impregnated cellulosic textile as above or under milderconditions of time and/or temperature; and at any time subsequent to thecure,

c. subjecting the cured cellulosic textile or articles manufacturedtherefrom to a heat treatment while constrained with or withourpressure, said heat treatment being of short duration and/or at mildtemperatures to produce sharp, permanent creases or other configurationsin the textiles or textile products. s

Percentage composition values as employed hereinafter refer to percentby weight.

The following list of examples is presented to illustrate this inventionand is not meant to limit its scope in any manner whatever.

EXAMPLE 1 Cotton twill fabric (7.6 oz/yd) was impregnated to wet pick-upwith a solution containing 12% of dimethyloldihydroxyethyleneurea(DMDHEU), 6% of cyclopentanetetracarboxylic acid (CPTA), 2% of anemulsified polyethylene softener, and 0.1% of a nonionic wetting agent.The fiber was dried on a pin frame in a forced draft oven for 8 minutesat 70C, then cured in the same equipment for 8 minutes at l60C. Afterwashing in water with a nonionic detergent, the fabric had an add-on of9.1% and a conditioned wrinkle recovery angle (WRA) (determined by theprocedure of ASTM designation 81295-67) of 306 (W+F), a wet WRA of 276(W+F), a Stroll flex abrasion resistance in the warp direction(determined by the method of ASTM designation D1 -64 T) of 30% of thatof the unmodified, laundered fabric, and a tearing strength in the tilldirection (measured by the Elmendorf method, as described in ASTMDesignation Dl424-63) of 50% of that of the unmodified control. Thesephysical properties are similar to those of cotton fabrics treated byconventional durable press processes.

A portion of the fabric was analyzed for nitrogen by the Kjeldahl methodand for formaldehyde by the chromotropic acid method. The fabric wasfound to contain 1.29% N and 1.43% formaldehyde. Another portion of thefabric was analyzed for saponification equivalent by a modifiedEberstadt method (as described by Tanghe, et al. in Methods ofCarbohydrate Chemistry," Vol. Ill, R. L. Whistler, Ed., 1963, pp.20l-203) and free carboxyl groups by a titration (as described byReinhardt, Fenner, and Reid in Textile Research Journal, Vol. 27, p. 873(1957). The fabric was found to contain 0.54 meq/g of saponifiablegroups (ester and carboxyl) and 0.33 meq/g of free carboxylic acidgroups. These analyses indicate that the textile contained crosslinksfrom the methylol reagent dimethyloldihydroxye- EXAMPLE 2 A portion ofthe textile prepared according to Example 1 was soaked in distilledwater, folded so that the warp yarns were bent, and placed on apreheated cloth surface. A thermocouple was placed between the sides ofthe fabric sample and the assembly was covered with a heated hand iron.The temperature of the iron was controlled by an apparatus attached tothe thermocouple. The fabric sample was heated at 160C for 5 minutes.After the creasing treatment, the fabric sample was rinsed in hot,running water, then stapled to a towel and subjected to five machinewashing and tumble drying cycles. After the last drying cycle, thecrease remaining in the fabric sample was evaluated by the AATCC method(AATCC Test Method 88 C-l969) modified as described by Hobart in TextileResearch Journal, Vol. 37, p. 380 (1967). The crease retained in thisfabric after the laundering cycles was rated at 4.3 on the AATCC scale(running from no crease to excellent). This example indicates that good,very durable creases are imparted to fabrics prepared according toExample 1 and treated according to this Example by a heat treatment. Themost reasonable explanation for the formation of durable creases in theheat treatment is that a recure (as defined above) occurred during theheat treatment and was catalyzed by the free acid groups in the fabric.

EXAMPLE 3 EXAMPLE 4 Cotton twill fabrics were treated according to theprocess of Example 1 except that the curing times were varied from 30seconds to 6 minutes. The fabric samples were given heat treatmentsaccording to the process of Example 2. The conditioned WRA and the AATCCcrease ratings after five launderings are reported in Table 1.

Table l Cure Time Cond WRA AA'ICC Crease (.W+F) Rating Table l-ContinuedCure Time Cond WRA AATCC Crease (,W+F) Rating 1.0 273 5.0 2.0 280 4.93.0 279 5.0 4.0 286 4.9 5.0 278 4.6 6.0 287 4.5

EXAMPLE 5 Cotton twill fabric was heated according to Example 1 exceptthat different concentrations f0 various polycarboxylic acids were usedin the treating solutions. These fabrics were creased according to theprocedure of Example 2. The conditioned WRA and AATCC crease ratingsafter five launderings are given along with the name and concentrationof the polycarboxylic acids in Table II.

Cotton printcloth (3.2 oz/yd) was impregnated with a solution containing8% of DMDHEU, 6.3% ofa polycarboxylic acid, and a trace of a nonionicwetting agent. The impregnated fabric samples were dried and curedaccording to the procedure of Example 1. The cured fabrics were creasedaccording to the procedure of Example 2. The concentration of DMDHEU,the polycarboxylic acid and its concentration are given along with theconditioned WRA and the AATCC rating of the crease remaining after thefive laundering cycles are given in Table III.

Table 111 Polycarboxylic Acid Cond. WRA AATCC Crease (.W+ RatingMellitic Acid 283 2.8 Tris(carboxyethyl)isocggnurate 258 2.8Benzophenonetetracar xylic Acid 286 4.2

EXAMPLE 7 Samples of cotton printcloth were impregnated with solutionscontaining 8% of a methylol crosslinking reagent, 4% of CPT A, 2% ofpolyethylene softener, and a trace of a nonionic wetting agent. Thefabric samples were dried and cured according to the process of Example1 and creased according to the process of Example 2. The methylolcrosslinking reagents, conditioned WRA and AATCC crease ratings afterfive laundering cycles are given in Table IV.

Cotton twill fabric was impregnated with a solution containing 20% ofDMDl-IEU, 20% of a highly methylated fully methololated melamine, andsufficient hydrochloric acid to lower the pH of the solution to 2.0. Thefabric was stored in the wet state for 24 hours, then washed to removethe excess reagents. The fabeic was then impregnated with a solutioncontaining 15% of mellitic acid, dried for 8 minutes at 80C, and curedfor 12.5 minutes at 160C. The cured fabric had a conditioned WRA of 265(W+F). This fabric was creased according to the process of Example 2.After five laundering cycles it had an AATCC crease rating of 3.3.

EXAMPLE 9 Cotton twill fabric was impregnated and dried according to theprocess of Example 3. Portions of this fabric were cured by heating thein an electrically heat hot-head press for 2 minutes at varioustemperatures between l30-and 205C. These fabric samples all had verygood smooth drying appearances and retained creases which were presentduring the heating process to repeated washing and drying cycles. Thisdemonstrates that at least a fair cure was obtained in all of thesamples by heating them in a hot-heat press.

EXAMPLE l Portions of the fabric prepared and cured in Example 3 werecreased according to the process of Example 2, except that a series ofdifferent times and temperature were used for the heat treatments. Thetimes and temperatures of the heat treatments are given along withcrease ratings of the fabrics after five washing and drying cycles inTable V.

A portion of the cotton twill fabric treated according to the process ofExample 3 was creased according to the process of Example 2. After fivelaundering cycles it had an AATCC crease rating of 4.0. Another portionof the fabric prepared according to Example 3 was given one washingcycle with an alkaline detergent, followed by tumble drying. This washedfabric was creased according to of process osf Example 2. After fivemachine wash and dry cycles this fabric retained a crease with an AATCCcrease rating of 1.7. A portion of the fabric washed with the alkalinedetergent was soaked in a water solution containing 5% acetic acid for30 minutes, then rinsed with distilled water. The acidified fabric wascreased according to the process of Example 2. After five washing anddrying cycles this fabric retained a crease with an AATCC crease ratingof 3.7.

EXAMPLE 12 Cotton twill fabric was treated according to the process ofExample 1 except that 6% of tetrahydrofurantetracarboxylic acid was usedin place of the cyclopentanetetracarboxylic acid. This fabric had aconditioned WRA of 309 (W+F). A portion of the fabric was subjected to aheat treatment according to the process of Example 2. After five washingand drying cycles, this portion of the fabric retained a crease rated at4.0 on the AATCC scale. Portions of the fabric were analyzed fornitrogen, formaldehyde, saponification equivalent, and free carboxylgroups by the methods given in Example 1. The fabric was found tocontain 1.14% nitrogen, 1.22% formaldehyde, 0.33 meq/g of saponifiablegroups, and 0.21 meq/g of free carboxyl groups. These analyses indicatedthat the textile contained crosslinks from the methylol reagentdimethyloldihydroxyethyleneurea (DMDHEU, chemically known as 1,3-bis(hydroxymethyl )-4,5-dihydroxy-Z-imidazolidinone) and ester and freecarboxylic acid groups from the polycarboxylic acidtetrahydrofurantetracarboxylic acid. The textile therefore consisted ofthe cellulosic derivative, the l,3-dimethylene-4,5-dihydroxy-2-imidazolidinone ether of cellulose tetrahydrofurantetracarboxylate.

EXAMPLE 13 Cotton twill fabric was treated according to the process ofExample 1, except that the impregnating solution contained only 4% ofcyclopentanetetracarboxylic acid and in addition contained 0.5% ofmagnesium chloride hexahydrate. The fabric sample was cured for 4 min,at C instead of for 8 min. at C. The fabric sample was not washed afterthe cure and had a conditioned wrinkle recovery angle of 298 (W+F). Asample of this fabric was subjected to a heat treatment according to theprocess of Example 2, except that the folded fabric sample was heatedfor 15 sec. at 160C. The fabric sample retained a crease rated at 5 onthe AATCC scale after five laundering cycles.

EXAMPLE 14 Cotton twill fabric was treated according to the process ofExample 13, except that 0.5% of zinc nitrate hexahydrate was used inplace of the magnesium chloride hexahydrate. This fabric had aconditioned wrinkle recovery angle of 303 (W+F) after the cure andretained a crease rated at 3.1 on the AATCC scale after the heattreatment and five laundering cycles.

EXAMPLE 15 Samples of cotton printcloth were impregnated with solutionscontaining 8% of DMDHEU, 3% of cyclopentanetetracarboxylic acid, 0.5% ofan activating catalyst, 2% of emulsified polyethylene softener, and atrace of 5 a nonionic wetting agent. The fabric samples were then driedat 70C for 8 min. and cured at 130C for 4 min. Portions of each of thecured fabric samples were subjected to heat treatments according to theprocess of Exmaple 2, except that the fabric samples were heated forsec. at 160C. The activating catalyst, the conditioned WRA of the curedsamples, and the AATCC crease ratings of the recured fabrics after fivelaundering cycles are given in Table VI.

Table VI Activating Catalyst Cond. WRA AATCC Crease W-l-F) RatingAluminum Chloride 315 3.0 Calcium Chloride 305 4.1 Magnesium DihydrogenPhosphate 296 3.5 Ammonium Chloride 302 3.6 Zinc Chloride 291 3.8Aluminum Chlorohydroxide 312 4.3

EXAMPLE 16 Cotton twill fabric was treated according to the process ofExample 1, except that the impregnating solution contained 4%cyclopentanetetracarboxylic acid and in addition contained 1% ofmagnesium chloride hexahyrate. The fabric sample was not subjected to ahigh temperature cure, but was stored at ambient temperature for 60days. After this time the fabric sample had a conditioned wrinklerecovery angle of 280 (W+F). A sample of this fabric was subjected to aheat treatment according to the process of Example 2, except that thefolded fabric sample was heated for 15 sec. at 160C. This fabric sampleretained a crease rated at 4.2 on the AATCC scale after five launderingcycles.

EXAMPLE 17 Samples of cotton printcloth were treated according to theprocess of Example 15, except that magnesium chloride hexahydrate wasused as the activating catalyst and the dried fabric samples were curedat different temperatures and for different times. Portions of the curedfabric samples were subjected to heat treatments according to theprocess of Example 2, except that the fabric samples were heated for 15sec. at 160C. The times and temperatures of the cures, the conditionedWRA of the cured fabric samples, and the AATCC crease ratings of therecured fabrics after five laundering cycles are given in Table V11.

Table Vll Cure Time Cure Temperature Cond. WRA AATCC Crease (min) (C.)W+F) Rating 14 EXAMPLE 18 Samples of cotton printcloth were treatedaccording to the process of Example 15, except that various concentrainsof cyclopentanetetrcarboxylic acid and magnesium chloride hexahyratewere used in the pad bath. The dried fabric samples were cured at 130Cfor 4 min. Portions of the cured fabrics were subjected to heattreatments according to the process of Example 2, except that the fabricsamples were heated for 15 sec. at 160c. The concentrations ofcyclopentanetetracarboxylic acid (CPTA) and magnesium chloridehexahydrate in the pad bath, the conditioned WRA of the cured fabricsamples, and the AATCC crease ratings of the recured fabrics after fivelaundering cycles are given in Table Vlll. ,33

1. An improvement in the process of impregnating a cellulosic textilewith a solution of a methylolated cellulose crosslinking reagent and apolycarboxylic acid having at least three carboxylic acid groups, curingthe textile and thermally reforming the cured textile, the improvementcomprising including from about 0.25 to 1.0 weight percent of a latentacid catalyst in said solution.

2. A process for thermally reforming a resilient,

moot ry n c l n e QQlLllQSlQ textile bs -v quent to the crosslinkingtreatment, which process consists of the following steps:

a. impregnating the cellulosic textile with a methylolated crosslinkingreagent augmented with from 1-6 weight percent of a polycarboxylic acidhaving at least three carboxylic acid groups and from 0.25 to 1.0 weightpercnt of a latent acid catalyst;

b. curing the impregnated cellulosic textile at a temperature notexceeding 160C. to produce a resilient, smooth-drying crosslinkedcellulosic textile, and

c. at any time subsequent to the cure, thermally reforming, withconstraint, the said crosslinked cellulosic textile at a temperature ofabout 160C. for a time interval of at least 15 seconds.

3. The initially crosslinked and subsequently thermally reformedcellulosic textile produced according to the process of claim 2.

1. AN IMPROVEMENT IN THE PROCESS OF IMPREGNATING A CELLULOSIC TEXTILEWITH A SOLUTION OF A METHYLOLATED CELLULOSE CROSSLINKING REAGENT AND APOLYCARBOXYLIC ACID HAVING AT LEAST THREE CARBOXYLIC ACID GROUPS, CURINGTHE TEXTILE AND THERMALLY REFORMING THE CURED TEXTILE, THE IMPROVEMENTCOMPRISING INCLUDING FROM ABOUT 0.25 TO 1.0 WEIGHT PERCENT OF A LATENTACID CATALYST IN SAID SOLUTION.
 2. A process for thermally reforming aresilient, smmoth-drying crosslinked cellulosic textile subsequent tothe crosslinking treatment, which process consists of the followingsteps: a. impregnating the cellulosic textile with a methylolatedcrosslinking reagent augmented with from 1-6 weight percent of apolycarboxylic acid having at least three carboxylic acid groups andfrom 0.25 to 1.0 weight percnt of a latent acid catalyst; b. curing theimpregnated cellulosic textile at a temperature not exceeding 160*C. toproduce a resilient, smooth-drying crosslinked cellulosic textile, andc. at any time subsequent to the cure, thermally reforming, withconstraint, the said crosslinked cellulosic textile at a temperature ofabout 160*C. for a time interval of at least 15 seconds.
 3. Theinitially crosslinked and subsequently thermally reformed cellulosictextile produced according to the process of claim 2.